2021-02-01 14:27:08

by Georgi Djakov

Subject: [PATCH] mm/page_io: Use pr_alert_ratelimited for swap read/write errors

If there are errors during swap read or write, they can easily fill
the log buffer and remove any previous messages that might be useful
for debugging, especially on systems that rely for logging only on
the kernel ring-buffer.

For example, on a systems using zram as swap, we are more likely to
see any page allocation errors preceding the swap write errors if the
alerts are ratelimited.

Signed-off-by: Georgi Djakov <[email protected]>
---
mm/page_io.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/page_io.c b/mm/page_io.c
index 92f7941c6d01..485fa5cca4a2 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -41,9 +41,9 @@ void end_swap_bio_write(struct bio *bio)
* Also clear PG_reclaim to avoid rotate_reclaimable_page()
*/
set_page_dirty(page);
- pr_alert("Write-error on swap-device (%u:%u:%llu)\n",
- MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
- (unsigned long long)bio->bi_iter.bi_sector);
+ pr_alert_ratelimited("Write-error on swap-device (%u:%u:%llu)\n",
+ MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
+ (unsigned long long)bio->bi_iter.bi_sector);
ClearPageReclaim(page);
}
end_page_writeback(page);
@@ -106,9 +106,9 @@ static void end_swap_bio_read(struct bio *bio)
if (bio->bi_status) {
SetPageError(page);
ClearPageUptodate(page);
- pr_alert("Read-error on swap-device (%u:%u:%llu)\n",
- MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
- (unsigned long long)bio->bi_iter.bi_sector);
+ pr_alert_ratelimited("Read-error on swap-device (%u:%u:%llu)\n",
+ MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
+ (unsigned long long)bio->bi_iter.bi_sector);
goto out;
}

2021-02-01 18:48:57

by Minchan Kim

Subject: Re: [PATCH] mm/page_io: Use pr_alert_ratelimited for swap read/write errors

On Mon, Feb 01, 2021 at 04:20:55PM +0200, Georgi Djakov wrote:
> If there are errors during swap read or write, they can easily fill
> the log buffer and remove any previous messages that might be useful
> for debugging, especially on systems that rely for logging only on
> the kernel ring-buffer.
>
> For example, on a systems using zram as swap, we are more likely to
> see any page allocation errors preceding the swap write errors if the
> alerts are ratelimited.
>
> Signed-off-by: Georgi Djakov <[email protected]>
Acked-by: Minchan Kim <[email protected]>

2021-02-02 02:19:54

by Miaohe Lin

Subject: Re: [PATCH] mm/page_io: Use pr_alert_ratelimited for swap read/write errors

Hi:
On 2021/2/1 22:20, Georgi Djakov wrote:
> If there are errors during swap read or write, they can easily fill
> the log buffer and remove any previous messages that might be useful
> for debugging, especially on systems that rely for logging only on
> the kernel ring-buffer.
>
> For example, on a systems using zram as swap, we are more likely to
> see any page allocation errors preceding the swap write errors if the
> alerts are ratelimited.
>
> Signed-off-by: Georgi Djakov <[email protected]>

Make sense for me. Thanks.
Reviewed-by: Miaohe Lin <[email protected]>

> ---
> mm/page_io.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/mm/page_io.c b/mm/page_io.c
> index 92f7941c6d01..485fa5cca4a2 100644
> --- a/mm/page_io.c
> +++ b/mm/page_io.c
> @@ -41,9 +41,9 @@ void end_swap_bio_write(struct bio *bio)
> * Also clear PG_reclaim to avoid rotate_reclaimable_page()
> */
> set_page_dirty(page);
> - pr_alert("Write-error on swap-device (%u:%u:%llu)\n",
> - MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
> - (unsigned long long)bio->bi_iter.bi_sector);
> + pr_alert_ratelimited("Write-error on swap-device (%u:%u:%llu)\n",
> + MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
> + (unsigned long long)bio->bi_iter.bi_sector);
> ClearPageReclaim(page);
> }
> end_page_writeback(page);
> @@ -106,9 +106,9 @@ static void end_swap_bio_read(struct bio *bio)
> if (bio->bi_status) {
> SetPageError(page);
> ClearPageUptodate(page);
> - pr_alert("Read-error on swap-device (%u:%u:%llu)\n",
> - MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
> - (unsigned long long)bio->bi_iter.bi_sector);
> + pr_alert_ratelimited("Read-error on swap-device (%u:%u:%llu)\n",
> + MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
> + (unsigned long long)bio->bi_iter.bi_sector);
> goto out;
> }
>
>
> .
>